* RE: [PATCH 1/2] mm: break up swap_writepage() for frontswap backends
[not found] <<1364874600-878-1-git-send-email-bob.liu@oracle.com>
@ 2013-04-02 20:27 ` Dan Magenheimer
0 siblings, 0 replies; 2+ messages in thread
From: Dan Magenheimer @ 2013-04-02 20:27 UTC (permalink / raw)
To: Bob Liu, akpm
Cc: linux-mm, minchan, sjenning, rcj, ngupta, konrad.wilk,
dan.magenheimer, Bob Liu
> From: Bob Liu [mailto:lliubbo@gmail.com]
> Sent: Monday, April 01, 2013 9:50 PM
> To: akpm@linux-foundation.org
> Cc: linux-mm@kvack.org; minchan@kernel.org; sjenning@linux.vnet.ibm.com; rcj@linux.vnet.ibm.com;
> ngupta@vflare.org; konrad.wilk@oracle.com; dan.magenheimer@oracle.com; Bob Liu
> Subject: [PATCH 1/2] mm: break up swap_writepage() for frontswap backends
>
> From: Seth Jennings <sjenning@linux.vnet.ibm.com>
>
> swap_writepage() is currently where frontswap hooks into the swap
> write path to capture pages with the frontswap_store() function.
> However, if a frontswap backend wants to "resume" the writeback of
> a page to the swap device, it can't call swap_writepage() as
> the page will simply reenter the backend.
>
> This patch separates swap_writepage() into a top and bottom half, the
> bottom half named __swap_writepage() to allow a frontswap backend,
> like zswap, to resume writeback beyond the frontswap_store() hook.
>
> __add_to_swap_cache() is also made non-static so that the page for
> which writeback is to be resumed can be added to the swap cache.
>
> Acked-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
> Signed-off-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Dan Magenheimer <dan.magenheimer@oracle.com>
> ---
> include/linux/swap.h | 2 ++
> mm/page_io.c | 14 +++++++++++---
> mm/swap_state.c | 2 +-
> 3 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 2818a12..76f6c3b 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -330,6 +330,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
> /* linux/mm/page_io.c */
> extern int swap_readpage(struct page *);
> extern int swap_writepage(struct page *page, struct writeback_control *wbc);
> +extern int __swap_writepage(struct page *page, struct writeback_control *wbc);
> extern int swap_set_page_dirty(struct page *page);
> extern void end_swap_bio_read(struct bio *bio, int err);
>
> @@ -345,6 +346,7 @@ extern unsigned long total_swapcache_pages(void);
> extern void show_swap_cache_info(void);
> extern int add_to_swap(struct page *);
> extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
> +extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
> extern void __delete_from_swap_cache(struct page *);
> extern void delete_from_swap_cache(struct page *);
> extern void free_page_and_swap_cache(struct page *);
> diff --git a/mm/page_io.c b/mm/page_io.c
> index 78eee32..8e6bcf1 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -185,9 +185,7 @@ bad_bmap:
> */
> int swap_writepage(struct page *page, struct writeback_control *wbc)
> {
> - struct bio *bio;
> - int ret = 0, rw = WRITE;
> - struct swap_info_struct *sis = page_swap_info(page);
> + int ret = 0;
>
> if (try_to_free_swap(page)) {
> unlock_page(page);
> @@ -199,6 +197,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
> end_page_writeback(page);
> goto out;
> }
> + ret = __swap_writepage(page, wbc);
> +out:
> + return ret;
> +}
> +
> +int __swap_writepage(struct page *page, struct writeback_control *wbc)
> +{
> + struct bio *bio;
> + int ret = 0, rw = WRITE;
> + struct swap_info_struct *sis = page_swap_info(page);
>
> if (sis->flags & SWP_FILE) {
> struct kiocb kiocb;
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 7efcf15..fe43fd5 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -78,7 +78,7 @@ void show_swap_cache_info(void)
> * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
> * but sets SwapCache flag and private instead of mapping and index.
> */
> -static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
> +int __add_to_swap_cache(struct page *page, swp_entry_t entry)
> {
> int error;
> struct address_space *address_space;
> --
> 1.7.10.4
--
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^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH 1/2] mm: break up swap_writepage() for frontswap backends
@ 2013-04-02 3:50 Bob Liu
0 siblings, 0 replies; 2+ messages in thread
From: Bob Liu @ 2013-04-02 3:50 UTC (permalink / raw)
To: akpm
Cc: linux-mm, minchan, sjenning, rcj, ngupta, konrad.wilk,
dan.magenheimer, Bob Liu
From: Seth Jennings <sjenning@linux.vnet.ibm.com>
swap_writepage() is currently where frontswap hooks into the swap
write path to capture pages with the frontswap_store() function.
However, if a frontswap backend wants to "resume" the writeback of
a page to the swap device, it can't call swap_writepage() as
the page will simply reenter the backend.
This patch separates swap_writepage() into a top and bottom half, the
bottom half named __swap_writepage() to allow a frontswap backend,
like zswap, to resume writeback beyond the frontswap_store() hook.
__add_to_swap_cache() is also made non-static so that the page for
which writeback is to be resumed can be added to the swap cache.
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
---
include/linux/swap.h | 2 ++
mm/page_io.c | 14 +++++++++++---
mm/swap_state.c | 2 +-
3 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2818a12..76f6c3b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -330,6 +330,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
/* linux/mm/page_io.c */
extern int swap_readpage(struct page *);
extern int swap_writepage(struct page *page, struct writeback_control *wbc);
+extern int __swap_writepage(struct page *page, struct writeback_control *wbc);
extern int swap_set_page_dirty(struct page *page);
extern void end_swap_bio_read(struct bio *bio, int err);
@@ -345,6 +346,7 @@ extern unsigned long total_swapcache_pages(void);
extern void show_swap_cache_info(void);
extern int add_to_swap(struct page *);
extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
+extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
extern void __delete_from_swap_cache(struct page *);
extern void delete_from_swap_cache(struct page *);
extern void free_page_and_swap_cache(struct page *);
diff --git a/mm/page_io.c b/mm/page_io.c
index 78eee32..8e6bcf1 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -185,9 +185,7 @@ bad_bmap:
*/
int swap_writepage(struct page *page, struct writeback_control *wbc)
{
- struct bio *bio;
- int ret = 0, rw = WRITE;
- struct swap_info_struct *sis = page_swap_info(page);
+ int ret = 0;
if (try_to_free_swap(page)) {
unlock_page(page);
@@ -199,6 +197,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
end_page_writeback(page);
goto out;
}
+ ret = __swap_writepage(page, wbc);
+out:
+ return ret;
+}
+
+int __swap_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct bio *bio;
+ int ret = 0, rw = WRITE;
+ struct swap_info_struct *sis = page_swap_info(page);
if (sis->flags & SWP_FILE) {
struct kiocb kiocb;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 7efcf15..fe43fd5 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -78,7 +78,7 @@ void show_swap_cache_info(void)
* __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
* but sets SwapCache flag and private instead of mapping and index.
*/
-static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
+int __add_to_swap_cache(struct page *page, swp_entry_t entry)
{
int error;
struct address_space *address_space;
--
1.7.10.4
--
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[not found] <<1364874600-878-1-git-send-email-bob.liu@oracle.com>
2013-04-02 20:27 ` [PATCH 1/2] mm: break up swap_writepage() for frontswap backends Dan Magenheimer
2013-04-02 3:50 Bob Liu
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